1. Field of the Invention.
This invention relates to a pressurized lubrication system for a power shaft and, more specifically, to such a power shaft which has a plurality of elements mounted thereon for independent rotation relative to the power shaft.
2. Description of the Prior Art.
There are a number of multi-drive vehicles which utilize a main transmission and a transfer case which is capable of providing power to the rear axle alone or to both the front and rear axles at the same time. Typical transfer cases of this type are disclosed in U.S. Pat. No. 3,095,758; 3,557,634, and 3,679,016.
It is not uncommon in transfer cases to include a means for providing a multi-speed power transmission function in the form of high and low speed operation. Transfer cases such as those disclosed in U.S. Pat. Nos. 3,941,199 and 4,188,838 include such features and significantly increase the selective operating gear ratios which are available to the operator of a vehicle which uses a main transmission in conjunction with the transfer case.
However, in vehicle transmission devices of this type, lubrication is often provided by the splashing of lubricating oil around the interior of the housing. The oil may be caught in channels or trays to be supplied to specific shaft bearings by gravity flow. However, in some configurations, gears or other elements may be mounted for relative rotation on shafts which, in turn, rotate to greatly reduce the effectiveness of splash or gravity lubrication. If these shafts are mounted in an upper region of the transmission housing remote from the oil sump, the reliability of this type of lubrication system is further reduced.